1. Field of the Invention
This invention relates to the field of mechanical joints for use in orthotic and prosthetic devices, specifically to an improved close contour mechanical joint primarily contemplated for orthotic use to assist the movement of an inadequately functioning body limb, the benefits of which include but are not limited to a compact configuration, enhanced joint strength, enhanced operational efficiency, decreased stress and wear on moving components, and enhanced user comfort and security. It comprises a distal bar having a large gear configuration integral to its proximal end and an opposed end that is configured for connection to orthotic hardware secured to the lower portion of a body limb, as well as a proximal bar (also referred to herein as a T-bar) having a T-shaped proximal end and an opposed end that is configured for connection to orthotic hardware secured to the upper portion of a body limb. For movement of the distal bar relative to the T-bar between positions of complete flexion and full extension (approximately the full 135-degree range of anatomical motion), the present invention also uses a snap ring, a brake wheel, and a transfer gear as part of its improved interior design. Therefore, instead of using a spring biasing member, as in prior close contour orthotic joints, the snap ring, brake wheel, and transfer gear (part of which is press-fit into a central area in the brake wheel), in combination with a gear configuration integral to the proximal end of the distal bar, produce a gear ratio reduction (preferably 2:1 in many orthotic applications) that allows a smaller stop increment for distal bar movement (approximately three degrees), less travel for each stop increment, less stress on gear teeth, and enhanced joint strength. In addition, as a result of its design improvements, less force is required to unlock the present invention close contour mechanical joint than is typically required for many currently used close contour joints for enhanced user convenience, and the T-bar is secured within a T-shaped recess in the joint's protective housing (hereinafter also referred to as the “main body”) for enhanced joint strength and compactness. When the present invention mechanical joint is in its fully extended orientation, the T-bar extends from the main body in a direction substantially opposite to that of the distal bar. Furthermore, a two-axis (co-linear) construction that further enhances joint strength and compactness is used for distal bar and T-bar connection to the main body, and in addition, the snap ring positioned around the present invention brake wheel (and having ratchet teeth that engage a pawl surface on the exterior of the brake wheel) is progressively moved into an opened position by a user employing a conveniently accessed handle connected to an unlocking pin having non-symmetrical perimeter configuration, with the opened snap ring position allowing free movement of the brake wheel (and thus free distal bar movement relative to the T-bar), and also with further rotation of the unlocking pin moving the snap ring again into it closed position wherein its ratchet teeth re-engage the brake wheel's pawl surface to provide one-direction brake wheel movement with incremental stops (and thus distal bar movement in the direction of maximum extension with a very small stop increment reduced by the gear ratio reduction of the transfer gear and the large gear configuration integral to the distal bar's proximal end). Although it is contemplated for use of the present invention to be primarily in orthotic devices, and particularly in orthotic devices used for infants and children, application in any device needing a mechanical joint for which the compact configuration and/or strength of the present invention would provide some assistance or technical advantage is considered to be within the scope of the present invention.
2. Description of the Related Art
Components used in orthotic devices and prosthetic devices should be compact and minimally intrusive for ease of use, enhanced social acceptability, and a lessened risk of hazard or damage during use. Further, a user should not experience insecurity, discomfort, or apprehension as a result of any aspect of their performance. As a fundamental part of their construction, all mechanical joints used in orthotic devices must include design features and/or apparatus that define the limits of their flexion and extension, and movement provided therebetween should avoid excesses and insufficiencies of motion. Often, mechanical joints are bulky in configuration, provide an abrupt stop for the user, and/or fail to provide proper support for a user when the joint nears maximum extension. Orthotic devices should also be as simple as possible for ease of manufacture and convenience during their function. The use of a snap ring, a brake wheel, and a transfer gear to provide improved interior design is new in the field of close contour orthotic joints. Instead of using a spring biasing member, as in many prior and currently used close contour orthotic joints, the snap ring, brake wheel, and transfer gear (part of which is press-fit into the brake wheel), in combination with a gear configuration integral to the proximal end of the distal bar, produce a reducing gear ratio (preferably 2:1 or close thereto) that allows a smaller stop increment, less travel, less stress and wear on gear teeth, and enhanced joint strength. In addition, less force is required to unlock it than is typically required for prior close contour joints. Furthermore, the distal bar and the T-shaped bar are pivotally connected to one another using a two axis (co-linear) construction that provides further compactness and operational efficiency in the present invention close contour mechanical joint. No other mechanical joint is known to have the same structure, function in the same manner, or provide all of the advantages of the present invention.